The role of fabrication process & choice of materials is one of significant impact on any given design. With the advent of 3D printing, a rapid tooling or prototyping process, it is sometimes even more critical since this approach is an additive process — building up material instead of removing it, as in a machining process. It is also significantly different from molding or casting since there is no die or ‘container’ present for support in critical areas. For those coming into CAD from rendering tools like 3D Studio, Maya, etc., or from virtual world environments, the significance — and subtleties of these issues may not be readily apparent.